The present invention relates to the field of analog-to-digital converters and more specifically to an apparatus and method for improving the accuracy and resolution of a digitizer.
During the process of converting analog signals to digital signals certain errors are introduced into the digital output signal. Typical sources of error are the well-known offset errors, scale factor errors, linearity errors and non-monotonicity. Another source of error is inherent in the quantization process itself.
Known as quantization or uncertainity error, this error occurs when a continuous signal is impressed on a quantizing device. The continuous signal is quantized by partitioning it into discrete ranges. All analog values within a given range are represented by the same digital code, which corresponds to a nominal mid-range analog input value.
A cut-point, designated as n, is defined as the analog input voltage at which it is equally probable that the digital output code will be n or n+1. There is, therefore, an inherent quantization error of .+-.1/2 least significant bit (LSB) present in the analog-to-digital conversion process. Previous methods of reducing this error voltage include increasing the number of bits in the output code.